反应详情

1-Cyclopropyl-8-(4-ethyl-1-piperazinyl)-7-fluoro-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid is prepared under the conditions of Reference Example 5 but starting from 2 g of 8-chloro-1-cyclopropyl-7-fluoro-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid and 2.74 g of 1-ethyl-piperazine in 20 cm3 of pyridine. The pure product is isolated after a first recrystallization from 105 cm3 of ethanol containing 25% of dimethylformamide followed by a second recrystallization from 75 cm3 of ethanol containing 50% of dimethylformamide. 0.67 g of 1-cyclopropyl-8-(4-ethyl-1-piperazinyl)-7-fluoro-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid is obtained in the form of a yellow-green solid melting at 254° C.

1. custom1-Cyclopropyl-8-(4-ethyl-1-piperazinyl)-7-fluoro-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid is prepared under the conditions of Reference Example 5
2. customThe pure product is isolated
3. customafter a first recrystallization from 105 cm3 of ethanol containing 25% of dimethylformamide
4. customfollowed by a second recrystallization from 75 cm3 of ethanol containing 50% of dimethylformamide